This makes way more sense. On 6/26/03 3:21 PM, "Ryan Ackley" <[EMAIL PROTECTED]> wrote:
> It may be related to the issue that we don't handle low performance > InputStreams in POIFS. If you have two processors only one of them can > control the PCI bus at any one. So if one attempts to read from the hard > drive it may not get anything until the other processor releases the PCI > bus. > > It is definitely I/O related because somehow the actual byte array that was > read from the workbook is being corrupted. Also, it only happens about 50% > of the time on my development machine. I have a scsi bus so that may explain > why it works for me some of the time and it happens in several different > places. I think a SCSI bus is more asynchronous than a pci bus. > > Avik, I don't think it has anything to do with the memory model because I am > running with dual xeon/Windows. The windows jdk uses the native threads > which use virtual memory. I can't think of a way that it would allow this to > happen. > > Ryan > > ----- Original Message ----- > From: "Avik Sengupta" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Cc: <[EMAIL PROTECTED]> > Sent: Thursday, June 26, 2003 11:25 AM > Subject: RE: Concurrency Issue > > >> Summary for those who came in late: Reading different files using >> different HSSFWorkbook objects in different threads works fine on a >> single processor box, but doesnt work on a multi processor box. >> >> I have the sinking feeling that we have hit some nice Java Memory Model >> issue. While Java Memory Model does not guarantee that multithreaded >> programs behave the same in single and multi-processor boxes, its >> actually very rare to see these errors in practice (incorrect concurrent >> access to a static variable, for example, will show up in a >> multithreaded program even on a single processor box. ) So its something >> much more subtle. >> >> The error is however quite consistent. I have tested on a dual proc >> Xeon/Linux and a dual Sparc/Solaris. >> >> The only workaround for now is that only one thread at a time reads a >> file into an HSSFWorkbook. >> >> Am continuing to look at it..tho am not very hopeful for an immediate >> fix.. its a dog to debug! >> >> On Fri, 2003-06-13 at 22:11, Avik Sengupta wrote: >>> [moving to poi dev] >>> I have now confirmed this issue. A simple program reading different xls >>> files in different threads using different instances of PoifsFileSystem >>> and HSSFWorkbook fails. >>> >>> I am currently unable to say further why this is so, since a quick look >>> at both POIFSFileSystem and HSSFWorkbook show no instances of static >>> data. Will look into this further. >>> >>> Regards >>> - >>> Avik >>> >>> >>> On Wed, 2003-05-14 at 14:41, Avik Sengupta wrote: >>>> I do not believe there are static stuff which precludes reading many >>>> files at a go, but i could be wrong. >>>> >>>> I would actually guess that one particular file of yours is throwing > up >>>> some pre-existing bug in poi. Have you checked that all the files you >>>> want to open can be opened sequentially in poi? >>>> >>>> On Tue, 2003-05-13 at 22:38, [EMAIL PROTECTED] wrote: >>>>> Hi Avik, >>>>> >>>>> Thanks a lot for the response. >>>>> I am creating diff. HSSFWorkBook for diff. uploaded files via diff. > threads. >>>>> But for some reason one of the WorkBook constructor fails. >>>>> >>>>> Can you please let me know if we have any limit on reading the files > concurrently >>>>> or any other part of the code( static stuff ) that may be causing > this issue. >>>>> >>>>> By the way, can I have your contact # or do you prefer to have my > contact # and >>>>> we can have a quick chat. >>>>> >>>>> Cheers >>>>> Vilay >>>>> >>>>> >>>>> -----Original Message----- >>>>> From: Avik Sengupta [mailto:[EMAIL PROTECTED] >>>>> Sent: Tuesday, May 13, 2003 5:53 AM >>>>> To: POI Users List >>>>> Subject: Re: Concurrency Issue >>>>> >>>>> >>>>> you cannot use a single HSSFWorkbook object from more than one > thread. >>>>> you will need to synchronise access to that object. Of course, you > can >>>>> use different HSSFWorkbook objects in different threads > concurrently. >>>>> >>>>> >>>>> >>>>> On Tue, 2003-05-13 at 02:00, [EMAIL PROTECTED] wrote: >>>>>> Hi Guys, >>>>>> >>>>>> I am having problem reading more than one file Excel files > concurrently. >>>>>> Reading individual files seem to be fine. >>>>>> >>>>>> The exception I get is as follows: >>>>>> >>>>>> java.lang.reflect.InvocationTargetException: > java.lang.ArrayIndexOutOfBoundsException >>>>>> at > org.apache.poi.util.LittleEndian.getNumber(LittleEndian.java:557) >>>>>> at org.apache.poi.util.LittleEndian.getInt(LittleEndian.java:177) >>>>>> at > org.apache.poi.hssf.record.DimensionsRecord.fillFields(DimensionsRecord.java > :121) >>>>>> at org.apache.poi.hssf.record.Record.fillFields(Record.java:143) >>>>>> at org.apache.poi.hssf.record.Record.<init>(Record.java:105) >>>>>> at > org.apache.poi.hssf.record.DimensionsRecord.<init>(DimensionsRecord.java:94) >>>>>> at java.lang.reflect.Constructor.newInstance(Native Method) >>>>>> at > org.apache.poi.hssf.record.RecordFactory.createRecord(RecordFactory.java:254 > ) >>>>>> at > org.apache.poi.hssf.record.RecordFactory.createRecords(RecordFactory.java:19 > 2) >>>>>> at > org.apache.poi.hssf.usermodel.HSSFWorkbook.<init>(HSSFWorkbook.java:191) >>>>>> at > org.apache.poi.hssf.usermodel.HSSFWorkbook.<init>(HSSFWorkbook.java:158) >>>>>> >>>>>> >>>>>> >>>>>> Your help is highly appreciated. >>>>>> >>>>>> Best Regards, >>>>>> Vilay >>>>>> >>>>>> Visit our website at http://www.ubswarburg.com >>>>>> >>>>>> This message contains confidential information and is intended > only >>>>>> for the individual named. 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Please >>>>> notify the sender immediately by e-mail if you have received this >>>>> e-mail by mistake and delete this e-mail from your system. >>>>> >>>>> E-mail transmission cannot be guaranteed to be secure or error-free >>>>> as information could be intercepted, corrupted, lost, destroyed, >>>>> arrive late or incomplete, or contain viruses. The sender therefore >>>>> does not accept liability for any errors or omissions in the > contents >>>>> of this message which arise as a result of e-mail transmission. If >>>>> verification is required please request a hard-copy version. 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